Serious congestion problems occur when multiple vehicles attempt to depart from or pass through a given location or route simultaneously, beyond a weather-specific threshold that the infrastructure can comfortably accommodate. For example, consider departures from a stadium following a college or professional football game. A large number of drivers depart from the same parking facilities through a limited number of exits and adjoining roadways. Each driver has the same information and expectations as every other driver. The vast bulk expect that their best chance to avoid stifling congestion and minimize the time during which they are stuck in traffic is to leave promptly when the game ends (or to leave early, especially if the game is not close), in order to beat the rush. Of course, the aggregate behavior of such drivers creates a huge traffic tie-up, making exit from lots difficult and time consuming, and further creating additional congestion on the routes leading away from the stadium after exiting the lot, often through several intersections. Any traffic information a driver receives from radio, other broadcasts, or apps such as Google Maps, is the same information obtained by every other driver from these sources. Information suggesting an alternative routing is often accepted by every driver receiving it, seriously diminishing what help that information could offer by creating congestion on the alternative route.
Similar problems are present in other scenarios in which a large number of people attempt to exit a fixed area in a given window of time. This applies not only to other situations in which crowds of people or vehicles attempt to depart events at roughly the same time, but evacuations in the event of natural or other disasters. For example, there has been no substantive progress in hurricane evacuations since Hurricane Katrina in 2005. Estimates of the average speed of evacuation during Katrina range from two to five miles per hour. As cars are limited to traveling much shorter distances on a tank of gas at those speeds, and at much higher engine temperatures, over 1,000 vehicles were reported pulled over on the shoulder of expressways, presumed overheated or out of gas. Additionally, in the attempt to get out of New Orleans, a large enough number of drivers chose to use an exit ramp onto the inbound lanes of expressways so as to substantially reduce average speeds and generate very hazardous driving conditions for first-responders trying to get into the city. As with the drivers leaving a stadium parking lot after a football game, everyone had the same information, and the same expectations about alternative routes. The evacuation order had been broadcast, and the vast majority of drivers started their cars and attempted to leave within minutes of that broadcast. There was no organized plan for evacuation of people without access to a car, or for families with only one car wanting to carry more persons, luggage, medicines and medical devices than the car could handle. When the possessor of the car sought to evacuate family members, low-speed travel crossing intersections where outbound travel was congested became difficult or impossible. For thousands of families, decisions as to the arrival target of evacuations were made without communication or coordination. In particular, children in school were taken to different locations than those chosen by their parents. Several newspapers reported thousands of cases of families unable to locate members for days afterward.
Similar congestion problems also occur whenever multiple vehicles or people attempt to move through a limited infrastructure simultaneously. Consider rush hour traffic. Over sixty years ago, William Vickrey (who later shared the 1997 Nobel Prize in Economics) wrote that average speed at the peak of rush hour could be dramatically increased if every driver ahead of the peak began her/his commute 10 minutes earlier, and every driver after the peak began 10 minutes later. No city or congested bridge (e.g., across the Hudson River, San Francisco or Chesapeake Bay, or at any international border) has found a way to take advantage of Vickrey's theory. Whether radio broadcasts, Google Maps, or Waze, every driver accessing a traffic information source has the same information. A small subset of drivers might be the ones who would benefit most from a given alternative route, because of the totality of their route and ultimate destination. However, these drivers have no way of knowing that. Slow speeds, long commuting times, increases in accidents, and frustration at a level affecting physical health, are all widespread. Similar issues exist with public transportation at rush hour. For example, overcrowded subway stops, as hordes try to catch the same trains at the same times, are neither pleasant nor conducive to good health or good behavior.
It would be desirable to address these issues.